The aim of this study is to assess the effects of substituting soybean meal with extruded urea in the diet of crossbred Texel x no defined racial pattern lambs under continuous grazing on Brachiaria ssp., focusing on both their productive and nutritional performance. 60 Texel crossbred lambs (12 animals for each treatment) were used, with an average initial weight of 20.7 ± 0.87 kg and an average age of 2.5 ± 0.70 months, fed treatments with increasing levels of UE (Urea extruded Amireia® 200S): 0; 6; 12; 18 and 24 grams of EU 100/kg of body weight, with trial period was 5 months, using the multivariate technique. The data were subjected to principal component and canonical discriminant analysis to check possible differences between the evaluated treatments and identify the variables that best discriminate and use these variables to create a discriminant function that represents the differences between treatments. Of the 12 variables initially used, we observed that 9 were used by the main components, but 6 were those that presented the greatest discriminatory power for the study. Main component 1 was characterized by biometric measurements and showed the greatest power of variation in the study (60%), followed by main component 2, represented by slaughter weight and empty body weight (13%). These correlations indicate that biometric measurements can serve as reliable indirect indicators for estimating carcass traits in sheep, offering a practical alternative to visual assessments.

Growth data on Jersey crossbred calves, maintained at ICAR-National Dairy Research Institute, Eastern Regional Station, Kalyani, Nadia, West Bengal, India, were collected and analysed to assess the influence of maternal effects on growth traits of calves. Traits considered for this study were birth weight (BW) and weights at 3 months (W3M), 6 months (W6M), 9 months (W9M) and 12 months (W12M) of age. Least-squares analyses were employed to obtain the effects of non-genetic factors on the traits of interest. Determination of influence of maternal effects on growth traits was estimated by fitting three univariate animal models (including or excluding maternal effects) using Bayesian approach. The most appropriate model for each trait was selected based on Deviance Information Criterion. Direct heritability (h2) estimates for BW, W3M, W6M, W9M and W12M were 0.31 ± 0.08, 0.26 ± 0.10, 0.48 ± 0.10, 0.44 ± 0.11 and 0.39 ± 0.14, respectively, under the best model. Permanent environmental maternal effects (c2) varied from 0.04 to 0.12 for all traits. Existence of maternal effects for all ages reflects the importance of maternal components for these traits. Moderate to high heritability estimates for growth traits indicate the possibility of modest genetic progress for these traits through selection under prevalent management system.

The objective of the current study was to evaluate the effects of breed and genomic inbreeding on 305-day lactation yields of milk, fat and protein; and fertility traits of pasture-based dairy cows in Argentina. The genomic inbreeding and heterozygosity of 890 first-lactation cows and 27 bulls were calculated through methods based on the genomic relationship matrix and run of homozygosity using 44 174 single-nucleotide polymorphisms. Cows were classified into four breed groups: Holstein, Holstein crossbred, Holstein–Jersey crossbred and Jersey crossbred. The effect of genomic inbreeding was not significant on production traits, but inbred cows increased 3.0 days calving to conception interval (CCI) per 1% genomic inbreeding. On average, purebred Holstein cows produced 1119 kg milk, 22 kg fat and 30 kg protein more than Jersey crossbred cows. In the case of the fertility traits, Jersey crossbred cows had 45 days shorter CCI than purebred Holstein cows. A possible reason for the non-significant effects of genomic inbreeding of production and fertility traits is that these effects were evaluated in a crossbred population in which rates of heterozygosity would operate to some extent in the opposite direction to rates of genomic inbreeding.

This study was conducted to estimate the relative contribution of dominance genetic effects to efficiency-related traits including Kleiber ratio (KR), efficiency of growth (EF) and relative growth rate (RGR) in Baluchi sheep. To this end, each trait was analysed with a series of 12 animal models which were identical for fixed and additive genetic effects but differed for combinations of dominance genetic and maternal effects. The Akaike's information criterion (AIC) was used to rank models. (Co)variances between traits were estimated using bivariate analyses. For all traits studied, according to AIC values, models containing the dominance genetic effects provided a better data fit than otherwise identical models. By including dominance genetic effects in the model, additive genetic variance did not change, but a significant decrease was observed in the residual variance (24, 19 and 25% for KR, EF and RGR, respectively). Estimates of dominance heritability $( {\boldsymbol h}_{\boldsymbol d}^ 2 )$ were 0.20 ± 0.05, 0.17 ± 0.05 and 0.19 ± 0.07 for KR, EF and RGR, respectively, more than corresponding estimates of additive heritability ${\bf ( }{\boldsymbol h}_{\boldsymbol a}^{\bf 2} {\bf ) }$ as 0.14 ± 0.02, 0.09 ± 0.03 and 0.13 ± 0.02, respectively. Dominance genetic correlations between traits were 0.89 ± 0.17 (KR-EF), 0.86 ± 0.20 (KR-RGR) and 0.93 ± 0.21 (EF-RGR). Additive genetic correlations between traits were 0.84 ± 0.05 (KR-EF), 0.78 ± 0.04 (KR-RGR) and 0.83 ± 0.04 (EF-RGR). The Spearman correlation between additive breeding values including and excluding dominance genetic effects were close to unity either for all animals or top ranked animals. Since presence of dominance genetic effects increased the model power to fit the data, inclusion of these effects in the genetic evaluation models for Baluchi sheep was recommended.

To investigate the potential application of replacing a proportion of a perennial ryegrass (PRG) silage diet with press cake on productivity and enteric methane (CH4) emissions in late lactation and non-lactating spring-calving dairy cows, a study was undertaken in which control cows (n = 21) were offered PRG silage, while treatment cows (n = 21) were offered a diet consisting of 60% PRG press cake and 40% of the same PRG silage. Although treatment cows had higher group average dry matter intakes (DMI) and produced more enteric CH4, carbon dioxide (CO2), milk solids, protein, fat- and protein-corrected milk yield (FPCM) in late lactation, the magnitude of the difference between treatment and control cows varied from week to week (P < 0.050). When enteric CH4 per kg of milk yield, milk solids and FPCM were considered, there was no significant difference between treatment and control. Absolute enteric CH4 was higher for cows fed press cake during the non-lactating period but this tended to vary from week to week. Similarly, CO2 (P < 0.001) and hydrogen (H2; P = 0.023) differed from week to week for cows offered press cake, and cows offered PRG silage in the non-lactating period. Although there was no significant effect of diet on body weight (BW) and body condition score (BCS), when enteric CH4 was expressed on a per kg BW basis, cows offered press cake tended to produce more enteric CH4 in both late lactation and during the dry period.

The interest in the search for alternatives to antibiotics in poultry production has been increasing, especially with the focus on essential oils due to their remarkable bioactive properties. This study aimed to investigate the effects of dietary supplementation of essential oils on the performance and gut morphometry of broilers, by using an approach of systematic review and meta-analysis. In the conduction of the systematic review, three electronic databases (PubMed, Science Direct and Scielo) were consulted in January 2023. Out of an initial amount of 162 papers, only 27 met the requisites to be included in the database. Furthermore, after the use of established criteria for the meta-analysis, only 16 papers were qualified for the evaluation of the aimed parameters. In the meta-analysis, it was observed that the supplementation had significant impact (P < 0.05) of 2.88% in weight gain, in comparison to the basal diet. In addition, the supplementation of essential oils significantly improved (P < 0.05) gut morphometry parameters such as villus height in the ileum (15.66% higher), and 8.26% increase in the villus height to crypt depth ratio in jejunum compared to the basal diet. Dietary essential oils improve the growth performance and gut histomorphometry of broilers, even when combined with antibiotics as growth promoters.